1. Field of the Invention
The present invention relates to a semiconductor device having multilayer interconnections, and to a production method therefor.
2. Description of the Related Art
FIGS. 7 and 8A show a semiconductor 100 having conventional multilayer interconnections.
The semiconductor device 100 includes a substrate 1, an epitaxial layer 2, an interconnection 3 of a first layer, an interconnection 4 of a second layer and a pad 6. The pad 6 is provided on the interconnection 4 of the second layer. The interconnection 4 of the second layer is used for shading light because it is necessary to prevent a photodetector incorporated into a circuit from being irradiated with light in order to avoid a circuital malfunction caused by irradiating the circuit. In other words, the interconnection 4 of the second layer is used as a shading layer or a light shield.
In the semiconductor device 100, the interconnection 4 of the second layer is connected to a portion having a low-impedance potential, such as a ground (hereinafter, referred to as GND), a positive power source, a negative power source or the like. As shown in FIG. 8B, the interconnection 4 of the second layer is connected to GND, the positive power source or the negative power source.
If a portion of interlayer insulation failure 50 occurred by disorder of production process, generation of a pin hole or the like during a production process of the semiconductor device 100, a defective interlayer insulation occurs between the interconnection 3 of a first layer and the interconnection 4 of a second layer. Furthermore, when the interconnection 4 of the second layer is used as a shading layer or a light shield, the interconnection 4 of the second layer is formed such that an area thereof is greater, thereby increasing the probability that an incomplete interlayer insulation will result.
As shown in FIG. 9, examples of a defective interlayer insulation include a short-circuit between the interconnection 3 of a first layer and the interconnection 4 of a second layer and an insufficient interlayer insulation in which an initial voltage resistance of the interlayer insulation is less than Vx. Even in a case where the interconnection 3 of a first layer and the interconnection 4 of a second layer are not short-circuited, a low voltage resistance of the interlayer insulation will result in a high probability that the semiconductor device will become defective after a certain time period.
When the interconnection 3 of a first layer and the interconnection 4 of a second layer are short-circuited, it is easy to detect the short-circuited semiconductor device. However, it has been difficult to detect a semiconductor device in which the interlayer insulation is insufficient.
In view of the above problem, an object of the present invention is to detect and eliminate a semiconductor device in which the interlayer insulation is insufficient.